# Redis is mostly single threaded, however there are certain threaded
# operations such as UNLINK, slow I/O accesses and other things that are
# performed on side threads.
#
# Now it is also possible to handle Redis clients socket reads and writes
# in different I/O threads. Since especially writing is so slow, normally
# Redis users use pipelining in order to speed up the Redis performances per
# core, and spawn multiple instances in order to scale more. Using I/O
# threads it is possible to easily speedup two times Redis without resorting
# to pipelining nor sharding of the instance.
#
# By default threading is disabled, we suggest enabling it only in machines
# that have at least 4 or more cores, leaving at least one spare core.
# Using more than 8 threads is unlikely to help much. We also recommend using
# threaded I/O only if you actually have performance problems, with Redis
# instances being able to use a quite big percentage of CPU time, otherwise
# there is no point in using this feature.
#
# So for instance if you have a four cores boxes, try to use 2 or 3 I/O
# threads, if you have a 8 cores, try to use 6 threads. In order to
# enable I/O threads use the following configuration directive:
#
# io-threads 4
# Set the max number of connected clients at the same time. By default
# this limit is set to 10000 clients, however if the Redis server is not
# able to configure the process file limit to allow for the specified limit
# the max number of allowed clients is set to the current file limit
# minus 32 (as Redis reserves a few file descriptors for internal uses).
#
# Once the limit is reached Redis will close all the new connections sending
# an error 'max number of clients reached'.
#
# IMPORTANT: When Redis Cluster is used, the max number of connections is also
# shared with the cluster bus: every node in the cluster will use two
# connections, one incoming and another outgoing. It is important to size the
# limit accordingly in case of very large clusters.
#
# maxclients 10000
127.0.0.1:6379> help @transactions
DISCARD (null) -- 放弃事务
summary: Discards a transaction.
since: 2.0.0
EXEC (null) -- 执行事务
summary: Executes all commands in a transaction.
since: 1.2.0
MULTI (null) -- 开启事务
summary: Starts a transaction.
since: 1.2.0
UNWATCH (null) --去掉监听
summary: Forgets about watched keys of a transaction.
since: 2.2.0
WATCH key [key ...] --监听某一个key的变化。key有变化后，就执行当前事务
summary: Monitors changes to keys to determine the execution of a transaction.
since: 2.2.0
使用方式也很典型，开启事务后，接入一系列操作，然后根据执行情况选择是执行事务还是回滚事务。例如
shell复制代码
127.0.0.1:6379> MULTI
OK
127.0.0.1:6379(TX)> set k2 2
QUEUED
127.0.0.1:6379(TX)> incr k2
QUEUED
127.0.0.1:6379(TX)> get k2
QUEUED
127.0.0.1:6379(TX)> EXEC --执行事务
1) OK
2) (integer) 3
3) "3"
127.0.0.1:6379> DISCARD -- 放弃事务
但是，这和数据库中的事务，是不是同一回事呢？看下面这个例子。
shell复制代码
127.0.0.1:6379> MULTI
OK
127.0.0.1:6379(TX)> set k2 2
QUEUED
127.0.0.1:6379(TX)> incr k2
QUEUED
127.0.0.1:6379(TX)> get k2
QUEUED
127.0.0.1:6379(TX)> lpop k2
QUEUED
127.0.0.1:6379(TX)> incr k2
QUEUED
127.0.0.1:6379(TX)> get k2
QUEUED
127.0.0.1:6379(TX)> exec
1) OK
2) (integer) 3
3) "3"
4) (error) WRONGTYPE Operation against a key holding the wrong kind of value
5) (integer) 4
6) "4"
--pipe Transfer raw Redis protocol from stdin to server.
--pipe-timeout <n> In --pipe mode, abort with error if after sending all data.
no reply is received within <n> seconds.
Default timeout: 30. Use 0 to wait forever.
2、使用案例
在Linux上编辑一个文件 command.txt。文件中可以包含一系列的指令
shell复制代码
set count 1
incr count
incr count
incr count
然后在客户端执行redis-cli指令时，就可以直接执行这个文件中的指令。
shell复制代码
[root@192-168-65-214 ~]# cat command.txt | redis-cli -a 123qweasd --pipe
Warning: Using a password with '-a' or '-u' option on the command line interface may not be safe.
All data transferred. Waiting for the last reply...
Last reply received from server.
errors: 0, replies: 4
[root@192-168-65-214 ~]# redis-cli -a 123qweasd
Warning: Using a password with '-a' or '-u' option on the command line interface may not be safe.
127.0.0.1:6379> get count
"4"
127.0.0.1:6379> eval "return {KEYS[1],KEYS[2],ARGV[1],ARGV[2]}" 2 key1 key2 first second
1) "key1"
2) "key2"
3) "first"
4) "second"
在lua脚本中，可以使用redis.call函数来调用Redis的命令。
shell复制代码
127.0.0.1:6379> set stock_1 1
OK
-- 调整1号商品的库存。如果库存小于10，就设置为10
127.0.0.1:6379> eval "local initcount = redis.call('get', KEYS[1]) local a = tonumber(initcount) local b = tonumber(ARGV[1]) if a >= b then redis.call('set', KEYS[1], a) return 1 end redis.call('set', KEYS[1], b) return 0 " 1 "stock_1" 10
(integer) 0
127.0.0.1:6379> get stock_1
"10"
################ NON-DETERMINISTIC LONG BLOCKING COMMANDS #####################
# Maximum time in milliseconds for EVAL scripts, functions and in some cases
# modules' commands before Redis can start processing or rejecting other clients.
#
# If the maximum execution time is reached Redis will start to reply to most
# commands with a BUSY error.
#
# In this state Redis will only allow a handful of commands to be executed.
# For instance, SCRIPT KILL, FUNCTION KILL, SHUTDOWN NOSAVE and possibly some
# module specific 'allow-busy' commands.
#
# SCRIPT KILL and FUNCTION KILL will only be able to stop a script that did not
# yet call any write commands, so SHUTDOWN NOSAVE may be the only way to stop
# the server in the case a write command was already issued by the script when
# the user doesn't want to wait for the natural termination of the script.
#
# The default is 5 seconds. It is possible to set it to 0 or a negative value
# to disable this mechanism (uninterrupted execution). Note that in the past
# this config had a different name, which is now an alias, so both of these do
# the same:
# lua-time-limit 5000
# busy-reply-threshold 5000
#!lua name=mylib
local function my_hset(keys, args)
local hash = keys[1]
local time = redis.call('TIME')[1]
return redis.call('HSET', hash, '_last_modified_', time, unpack(args))
end
redis.register_function('my_hset', my_hset)
注意，脚本第一行是指定函数的命名空间，不是注释，不能少！！！
然后，就可以使用Redis客户端，将这个函数加载到Redis中。
shell复制代码
[root@192-168-65-214 myredis]# cat mylib.lua | redis-cli -a 123qweasd -x FUNCTION LOAD REPLACE
Warning: Using a password with '-a' or '-u' option on the command line interface may not be safe.
"mylib"
[root@192-168-65-214 myredis]# redis-cli --help
...
--bigkeys Sample Redis keys looking for keys with many elements (complexity).
--memkeys Sample Redis keys looking for keys consuming a lot of memory.
